Can you have too much Organic Matter?

[holwellcourtfarm]

There is a soil scientist at a certain southwest university who refuses to accept that grassland will sequestrate carbon, apparently only temporary cover crops can do that?!

Every "scientist" in the carbon field should have their personal beliefs stated clearly before their "research" findings are analysed I'm afraid. So many are pushing a personal agenda.

 

[Nick Adams]

We've been increasing OM for about 10 years and have grassland fields at 18% now.

I have been told the figure will plateau at some point (although no one can tell me when) The soil will still build carbon, but not as a %, but you will continue to build soil if that makes sense. We have entered into a load of extra testing as the results as measured (30m grids across a field and at 3 depths, sent to 2 labs and through 3 organisations) got results that are apparently impossible to achieve according to some, and has caused a lot of arguing between 2 factions of soil scientists.

Soil biology is quite good at metabolising chemicals, so I think some of the chemical guys recommend keeping OM low to improve the effectiveness of chemical control.

WOW!

What was your starting base, and what have you been doing to increase levels please?

Indirect evidence should be adequate to prove the utility of OM ie. productivity, input use, profitability etc.

 

[mikep]

This question is poorly thought or mischievous.
It's the same as 'can you have too much beer'.
Depends on too many factors to quantify or qualify, put some on each year and the answer is no, but put 200t/a of sewage sludge on and the answer is yes.
In an established soil it just goes from mineral to organic depending on the OM but is peat bad?

 

[Kiwi Pete]

This question is poorly thought or mischievous.
It's the same as 'can you have too much beer'.
Depends on too many factors to quantify or qualify, put some on each year and the answer is no, but put 200t/a of sewage sludge on and the answer is yes.
In an established soil it just goes from mineral to organic depending on the OM but is peat bad?

Peat is actually pretty good - for plant life.
Otherwise those billions of seedlings that I potted up during school holidays wouldn't have been grown in it, but it is remarkably sterile.
In that sense so is a newborn child, until you touch it, and then your microbial print is transferred onto the child - I suppose this is the horticultural equivalent in a way.

The main issue of course is that it can quickly become anaerobic, of course; and that's not compatible with life, or nutrient cycling, or much else - hence why that peat was so sterile